Manufacture of zinc white



Aug. 25; 1931. J. MIH. CORNILLAT MANUFACTURE OF ZINC WHITE Filed July 9, 1927 3 Sheets-Sheet l m NH 1931. J. M. H. CORNIITLAT 1,820,598

MANUFACTURE OF ZINC WHITE Filed July 9, 1927 I5 Sheets-Sheet 2 II/Il/IIII/I/II/II/A Z IIA i ziuemioi; fide vluilazwa J/e/zm' firm Aug; 1931. J. M. H. CORNIL LAT 1,820,598

MANUFACTURE OF ZINC WHITE Filed July 9, 1927 5 Sheets-Sheet 3 j MW I Patented Aug. 25, 1931 1 UNITED-STATES PATENT OFFICE,

JOSEPH -MARGEL: HENRI, ooRmLLA'r, or PAR-IS, sermon MANUFACTURE OF ZINC WHITE Application fi1ed I111y 9,l...1927,' Seria1 110,204,603, and in France J'u1y 15; 1926.

"" metal to the oxide i's'not'completely effected because the bath of metal is motionless. Consequently, it is necessary-t frequently break up the superficiallayer ofoxide which forms on its surface, and for th is purpose a poker or similar apparatus is used. The use of such an implement is wasteful of time and labor and does not result in the proper quality of zinc oxide. My process avoidsth'is disadvantage and others commonto the processes here- 20 tofore used, as will appear hereafter. V

. Aimetal furnace, of" cylindrical shape, for

example, is providedysupported on rollers and lined'iwith suitable refractory material, and equipped with a fuel or oil gas burner for-heating urp oses; the flame of the burner being cause to travel in a U-shaped path owing to the fact that the burner nozzle is disposed in the same wallof thefurnace as the gas outlet: The refractory walls of the furnace are heated to white heat, and then the metallic zinc, either: pure or mixed, is introduced into the furnace, melts therein, and is rapidly broughtto'boiling temperature.

,Theburne'r is placedin the upper part of the furnace and is inclined so thatthe flames are first projectedviolently downward and toward the opposite end of the furnace by the air under pressure required for the atomization and combustion of the oil, and then return toward the gas, outlet,.lickingdirectly over the bath of molten'metal. An intense liberation of zinciferous vapors results therefrom',; the vapors rushing at considerable speed toward the opening provided below as the burnerfor the escape of the gases and passing through a short metal pipe of suitable form lined withcrefractory material, which leads from the furnace to an oxidizing chimney of refractory material. The zinc- -the outside thereof, letsthe hot gases escape iferous vapors enter the chimney through this pipe and then escape from it and pass through a metal pipe of suitable length disposed at the top of the chimney which opens into a large condensing chamber. v The latter chamber is of the simplest char- "i; acter: it consists of, a large space orcompartment situated within abuilding of suitable dimensions for thepurposein question, such space being entirely closed or'confined on all sides by canvas. A current of atmos- 6 pheric air circulates between the walls of the building and those of the canvas chamber,which are separated or spaced from each other for that purpose, and thelower part of the said chamber is constructed of intersecting cross-pieces, beneath which a man can easily pass'upright and between whichthe canvas is arranged in the form of pockets that are opened at the time of collection to enable the-deposits of zinc white to be dis- '70 charged. v v

In order to avoid the formation of a crust on the" bath of molten metal and consequent pokingto' break up the same, the furnace is N rocked forward and backwardon its rollers "by a suitable mechanism which has the effect of stirring or agitating the zinciferous liquidin such a way that 1t meets at regular 1nterva'ls' a wall of refractory material which is'not'covered with the zinc and which is subjected to the action of the fiame, Hence, the liberation of the zinciferous" vapors is considerably increased, and the bath of zinc in permanent contact either with theflame or with thefwhite-hot refractory material iscompletely exhausted.

' The condensing chamber, the canvas sides of which are constantly shaken or agitated by the current of atmospheric air circulating on at its upper part and sides, and the draft through the furnace is thus established without other agency; Charging of the metal takes place at regular intervals through a' door located atthe opposite end of the fur? nace from the burner and the gas outlet; and the slag, when there is any, is removed through the door by scrapers before the charge is introduced. i Collection of the zinc white can be eifected about a quarter of an hour after the first charging, which itself occurs about two hours after the furnace is fired. In consequence, it will be apparent, the present process avoids the necessity for continuous operation, as production can be suspended for rest days without having any damaging effect on the refractory material.

According to its destination, the zinc white obtained can be left as it stands, on leaving the condensing chamber, or can be bleached by passing it through a coke furnace where it undergoes a roasting treatment in known manner.

In order to afford a more complete understanding of the invention one form of apparatus for carrying out the invention has been illustrated in the accompanying drawings; but no claim for such apparatus has been made herein, as the apparatus forms the subject of my copending application, No. 204,604, filed of even date with the present case, and has matured to Patent No. 1,751,396 dated March 18, 1930.

In said drawings Figures 1 and 2 are horizontal and vertical sectional views, respectively, of a somewhat diagrammatic character and with parts in plan and elevation, of the complete installation;

Fig. 3 is an enlarged plan view of the furnace and oxidizing chimney;

F ig. 4 is a side elevation of Fig. 3, but with the furnace rocking mechanism omitted and the furnace itself partly in section;

Fig. 5 is a detail section on line 55, Fig. 4.

Referring more particularly to the drawings, 1 indicates generally a metal furnace provided with a refractory lining 2 and supported on rollers 3, the furnace shown being of cylindrical form and heated by means of a burner 4. A short metal pipe 5 having an internal refractory lining 25 connects the furnace with the oxidizing chimney 6, and the latter, in turn, is connected by the pipe 7 to the condensing chamber 8. The pipe for discharging the products of combustion from the chimney to the outside is indicated at 9.

The condensing chamber 8 which, as previously stated, has its walls 11 made of canvas, is disposed within a building 10, the walls of which are spaced from those of said chamber to enable the circulation around the chamber of a current of air that enters through the lower openings 13 and escapes at the top of the building through the openings 14 in the roof. as indicated by the arrows 12. The collecting pockets of the con {lensing chamber are designated 15:. the hotgases delivered to said chamber filtering through the canvas ton and side walls of the chamber.

The metallic zinc in pure or mixed state is introduced into the furnace through a door 16 provided in the end wall 17 thereof, and to said wall there is secured a stud or pin 18 that is connected by a rod 19 to a flywheel 20; the latter being secured to a driving shaft 21 which is itself rotated in any desired manner. In consequence, the furnace is caused to rock to and fro on its supporting rollers, its movement being controlled by flywheel 20.

At 22 is represented a fan driven by a motor 23, the outlet side of the fan being connected by a flexible pipe 24 with the burner l to supply thereto the air required for combustion and for the pulverization of the oil. The pipe 24 does not open directly into the burner, however, but, instead, opens into an annular space or chamber 55 (Fig. 5) provided in the exhaust pipe 5 between the outer metal shell thereof and the refractory lining 25, so that the air thus passes around said lining before it enters the burner and is preheated by the hot gases flowing through the inner portion of the pipe enclosed by the lining. The oil is supplied to the burner by a flexible pipe 26 which leads thereto from a tank 27 attached to the chimney 6; and under the pressure of the air supplied by the fan or blower 22, the finely pulverized oil is projected toward the door 16 in a flame which turns back and travels toward the exhaust pipe 5 after having licked across the zinciferous material 28, so that the flame may thus be regarded as moving in a U-shaped path.

Due to this movement or travel of the flame, it is possible to utilize completely the heat produced, while the preheating of the combustion air by circulation through the annular space 55 adds further to the economy in oil. It will be understood, of course, that the admission of both air and oil can be regulated by suitable valves which will enable the desired temperature to be obtained.

An opening 29 may be provided in the wall. of the furnace through which the operation may be observed and, if necessary, a poker inserted to determine how far the operation has advanced. In the case of metal containing impurities, cleaning can be effected through door 16 which is opened for each charge after the furnace has been stopped and before it is heated and the rocking mechanism is started. A cleaning opening 30 is also provided in the chimney 6 for removing the Zinc white and the'slag discharged from the furnace.

I claim as my invention:

A process of making zinc white, comprising the steps of feeding fuel oil and preheated air under pressure to a burner for admixture therein and projecting the flame from the burner into a closed furnace to heat the walls thereof; introducing into the furnace, after its walls have been brought to white heat, acharge of metallic zinc to form a molten bath, with relation to which bath said flame is caused to travel in a U-shaped path first 

